Fluid pressure control device



Dec. 26, 1944. L. A. MAJNERi 2,366,119

FLUID PRESSURE CONTROL DEVICE Filed'Sept. 14, 1942 2 Sheets-Sheet 1INVENTOR.

LUDWIG AL MAJNERI ATTORNEYS Dec. 26, 1944.

2 Shets-Sheet 2 Filed Sept. 14, 1942 INVENTOR. LUDWIG AMAJNE'RIATTORNEYS vide an improved fluid Patented Dec. 26, 19,44

Ludwig A. Majneri,

to The Warner Grosse Pointc, Mich, assignor Aircraft Corporation,Detroit, Mich., a corporation of Mic higan,

{\pplication September 14, 1942, Serial No. 458,264 9 Claims. (01. GO-54.6)

The invention relates to fluid pressure control devices andrefers moreparticularly to fluidpressure control devices for hydraulic brakes.

The invention has for one of its objects to propressure control deviceof the compound type having a low pressure producing means and a highpressure producing means adapted to operate successively in produc; ingfluid pressure.

The invention has for another of its objects to provide an improvedmechanism for control ling thechange-over from the effective operationof the low pressure producing means to the eifec tive operation of thehigh pressure producing means during the advance or pressure stroke ofthe device.

The invention has for other objects to provide the change-overcontrolling mechanism with a valve .and with adjustable means forcontrolling the movement of the valve; to provide the change-overcontrolling mechanism with means for limiting movement of thevalvetosecure approximately the same effective advance or pressure strokeregardless of the speed of advanc'e; to provide the change-overcontrolling mechanism with means for resiliently opposing movement-ofthe valve in a manner to approximately compensate for difierent brakecharacteristics; to provide the change-over controlling mechanism withmeans for opposing movement of the valve approximately in accordancewith "the viscosity of the fluid; and to provide the change-overcontrolling mechanism with a plunger for operating the valve and withmeans engageable with the plunger to oppose a resistance to itsmovement.

The inventionhas for further objects to provide a fluid pressure controldevice in which the low pressure producing and the high pressureproducing means comprise low pressure and high pressurecylinders andpistons slidable within the cylinders and adapted to be directly movedfrom position by a piston rod which serves to conductfluid from the highpressure cyl nder to hold a valve in open position and thereby allowfluid in the low pressure cylinder to flow to a reservoir,

In the drawings:

Figure l isa vertical central section through a fluid pressurecontroldevice embodying my invention; i v i v Figure 2 is a similarviewshowing the parts in a different position during the operation ofthe device; 7 Figures 3 and 4 are cross sections'on the lines 3-3 and4-4, respectively, of Figure 1;

Figures 5 and 6 are; views similar to Figures 1.

and 2, respectively, showing another embodiment of the invention;

Figure 7 is a viewsimilar to aportion of Figure 1 showing anotherembodiment of the invention. The fluid pressure controldevice isparticularly applicable to a hydraulic brake system of an. airplane, butit is apparent that the devicemay be used with other hydraulic brakesystems, While the devices, as shown, do notfincorpdrate the A parkingfeatures of my Patent No. 2,115,174, issued April 26, 1938, or my PatentNo; 2,120,073, issued June 7, 1938, the parking features maybe readilyincorporated in accordance with "the teachings of the patents.

The fluid pressure control device generally comprises highpressureproducing means, low pressure producing means, a reservoir, andmechanism for controlling the change-over from the efiective operationof the low pressure producing means tothe effective operation'ofthe'high pressure producing means during the advance or pressure strokeof the device. As illustrated, the dewhereby the low pressure cylinderisrelieved; and

vice occupies asubstantially vertical position and comprises ahighpressure chamber inits lower portion, a low pressure chamberabovethe high pressure chamber, and a reservoir above the low pressurechamber and in the upper portion of the device. The high pressurechamber is adapted to d scharge fluid under pressure, through adischarge port which is adapted. to be connected by tubingto a wheelcylinder for actuating a brake. The low pressure chamber is adapted todischarge fluidunder pressure to the high pressure chamber until apredetermined pressureof fluidin the low pressure chamber iscreated, atwhich time the change-over controlling mechanism places the low pressurechamber in communication with the V reservoir. Then when a predeterminedpressure;

of fluid in the high pressure chamber is created, the fluid in thehighpressure chamber operates upon the change-over controlling mechanismto hold the low pressure chamber'incommunication the lowpressurechamber. I

Referring to Figures 1 to 4, inclusive, the fluid with the reservoirindependently of the fluid in (not shown).

' from the reservoir past the fitting.

pressure. control device has the lower high pressure cylinder the upperlow pressure cylinder 2 of larger diameter-than the high pressurecylinder, and the braking fluid reservoir 3 above the low pressurecylinder. The fluid pressure -contro1 device also has the high pressureand low pressure pistons 4 and 5, respectively, slidinder for actuatinga brake by the usual tubing The reservoir 3 is closed at its upper endby'the upper end fitting |l fixedly secured to the reservoir. Thefitting has the depending annular flange l2 which is preferably threadedinto the reservoir and which is provided with the external annulargroove l3 and the radial passageways 4 leading from the groove to thechamber within the annular flange. The groove opens into the port l5which i adapted 'to be connected to an. auxiliary braking fluidreservoir. |6is a sealing ring above the annular groove for preventingthe leakage of braking fluid Thepiston rod 6 is constructed to bepivotally connected to a suitable foot pedal for longitu dinally movingthe piston rod downwardly to operate the control device; The fitting His provided with a suitable bushing l1 for engaging a 'pivot'pin of asuitable support.

The lower high pressure piston 4 has the annular head l3 slidable withinthe high pressure cylinder I and the upwardly extending sleeve l9 formedof the reduced portion and the enlarged portion 2 The upper end of thereduced portion has the annular valve seat 22 and the lower end of theenlarged portion has the transverse ports 23. The piston rod 6' slidablyextends through the annular head and sleeve. The high pressure pistonalso has the annular sealing cup 24 preferably formed-of rubber andprovided with concentric lips for slidably engaging the wall of the highpressure cylinder and the piston rod 6. Thehead I8 is formed withthetransverse ports 25 for permitting the flow of the braking fluid fromthe low pressure cylinder to the high pressure cylinder. A resilientthin sheet metal disc 24' is preferably provided between the head I 8and the sealing cup 24 to prevent the latter from being forced'into thetransverse ports 25. Also a circular cross sectioned ring 24" preferablyformed of rubber is preferably provided between the head I8 and thepiston rod 6 to prevent the flow of the braking fluid therebetween-During the flow of the braking fluid from the low pressure cylinder tothe high pressure cylinder through the transverse ports both theresilient disc and the sealing cup are flexed. The low pressure piston 6has the body 26 and the annular head 21 which are fixedly secured to theupper end of the enlarged portion 2| of the sleeve of the high pressurepiston. As shown, the-body 26 is threaded into the upper end of theenlarged portion 2| and has the annular flange "which extends over andclamps the annular head 21 against the annular The is closedat its lowerend high pressure cylinder by suitable means and, as ,shown,' isthreaded at 3 into the high pressure cylinder- The high pressurecylinder is provided.- near its lower end with the discharge port l0which is adapted to be connected to a wheel cylv of shoulder 23 formedon the enlarged portion 2|.

I preferablyprovide the sealing ring 30 between the annular flange andhead. The low pressure piston also has the flanged sealing ring 3|preterably formed of rubber and abutting the lower side of the head 21and provided with an outer lip which slidably engages the wall of thelow pressure cylinder 2. The sealing ring is clamped by the head 21against the annular shoulder 32 formed on the enlarged portion 2| of thesleeve of the high pressure piston. The head 21 is formed with thetransverse ports 33 for permitting the flow of braking fluid fromthereservoir to the low pressure cylinder, during which time the sealingring 3| is flexed.

The piston rod 6 has at its upper end the enlarged cup-shaped portion 34which i located within the enlarged portion 2| of the high pressurepiston sleeve. The bottom of the cup-shaped portion is provided with theannular ring 35 preferably formed of rubber and constituting a valvewhich is adapted to seat on the valve seat 22. The piston rod isprovided with the. axial passageway 36 and the radial passageways 31 and38 leading from the axial passageway, the'passageways 31 being below thesealing cup 24 and the passageways 38 being immediately below the valve35. 39 is a retractingcoil spring, 'for resiliently holding the pistonrod 6 in its of! position. This coil spring abuts the sealing cup 8 andthe annular shoulder 40 formed upon the annular wall 4| of thecup-shaped retainer 42. The retainer is held from upward movementrelative to the piston rod by suitable means, suchas the cwasher 43within the retainer and engaging an annular groove in the piston rod. Toprevent sticking of the sealingcup 24 during the return is slotted sothat the axialipassageway of the piston rod is always in communicationwith the high pressure cylinder. 44 .is a second retracting springlocated betweenthe low pressure piston and the piston rod forresiliently holding both'the low pressure piston and the high pressurepiston in their off position. As shown, the retracting spring 44 is acoil spring abutting the body. 26

of the low pressure piston and the nut 45 which is threaded into theupper end of the enlarged .cupshaped portion 34 of the piston rod.

With the parts as thus far described, the high pressure piston and thelow pressure piston are fixedly connected to each other and move inunison. Downward movement of the piston rod.6 v

through its valve 35 abutting the seat 22 advances both pistons andthe'piston rod and both pistons and the piston rod are adapted to beretracted to their off position by the coil springs .39 and 44. The coilspring 39 acts upon the piston rod to retract the same and the coilspring 44 acts upon the pistons to retract the same. The off position ofthe pistons is determined by abutment of the annular head 21 of the lowpressure piston with the lower end of the annular flange |2 of the upperend fitting while the ofi position of the piston rod is determined bythe change-over controlling mechanism which is later described and whichpositions the piston rod relative to the pistons so that the valve .35is spaced from the valve seat 22, at which time the high pressurecylinder is in communication with the low pressure cylinder. It will benoted that during the advance of the pistons braking passageways fluidis discharged from the low pressure cylinder into the high pressurecylinder through the ports 25 and past the resilient disc 24' and thesealing cup 24 and that during the retraction of the pistonrod andpistons brakingfluid may pass from the high pressure cylinder to the lowpressure cylinder through the passageways 31, 35 and 35 of the pistonrod between the separated valve 35 and seat 22 and through theports 23in the high pressure piston sleeve. Braking fluid may also pass from thereservoir to the low pressure cylinder through the ports 33 in the head21 of the low pressure piston and past'the sealing ring 3|. a

To relieve the fluid pressure in the low pressure cylinder during theadvance or pressure stroke of the fluid pressure control device. I havei provided a change-over controlling device for placing the low pressurecylinder in communica- .tion with the reservoir. The mechanism is firstoperated by the fluid in the low pressure cylinder to open thecommunication and then operated by the fluid in the high pressurecylinder to hold the communication open, thereby completely relievingthe fluid in the low pressure cylinder from pressure except that of thehydraulic head of the fluid in the reservoir. g

In detail, the body 25 of the low pressure piston is annular andprovides an axial passageway 45 therethrough, the uper portion of whichis nlarged. The upper portion of the annular flange 25 of the body isprovided with the aligned radial grooves 41 forplacing the enlargedportion ofthe axial passageway in communication with the reservoir. Toplace the reduced port on of the axial passageway in communication withthe low pressure cylinder,

I have provided the radial high pressure piston sleeve and the externalannular groove 49 in the body 25 registering with the radial passageways48 and also the radial passageways 50 in the body 25 leading fr m theannular groove to the axialpassageway. is a ball valve within theenlarged portion of the axial passageway 46 and adapted to seat up n theannular seat 52 which is formed in the body 25.

For unseating the ball valve or raising it from its seat, I haveprovided the plunger 53 having its upper end engageable with theballvalve and ring within the cup-shaped enlargement 34 and having its baseheld against the nut 45 by the spacer 55. The sealing ring ischannel-shaped 48 in the enlarged portion 2! of the in cross section andhas an outer lip engaain' the annularwall oi the cup-shaped enlargement34 and an inner lip engaging the plun er 53 which extends through andslidablyen ages the nut 45. The length of the plunger 53 is such thatwhen the piston rod and the pistons are in oil? position the piston rodabuts the lun er and it, in *turn, abuts the ball valve and holds thesame 01f its seat. However, as soon as the piston rod is advanced toengage its valve 35 with the valve seat 22 the plunger is loweredandtheball valve engages its valve seat.

4 For guiding and controlling the movement of me a dependingannularflange extending freely within the enlarged portion or the axialpassage way 45 of the low pressure piston and encircling the ball valve5| and having its body engageable with the ball valve. The bottom 01'the plunger is resiliently held against the ball valve bythe coil spring51 which at its lower'end abuts the yoke or bar. 55 secured to theplunger as by ex-.

tending diametrically .therethrough in registration with the grooves 41.The upper end of the coil spring abutsthe collar 55 which is mounted 0nthe,,annular flange 54, which latter extends upwardly from the annularbody 25 of the low pressure piston and, more particularly, the annularflange 25 01' the body. Thecollaris, ad- Justably threaded on theannular flange to allow change of pressure of the spring for resilientlyholding the ball valve in closed position to there.- by approximatelycompensate-tor the diiier'ent,

characteristics of the various brakes with which the fluid pressurecontrol device may be used so that uniform braking action maybe secured-To oppose movement of the ball valve approximately in accordancewithqthe viscosity of the braking.

fluid, the plunger 55 is constructed to cooperate with the cylinder 5|in a manner to effect a dashpot action. The plunger slidably engages thecylinder and, as shown, is provided with the series of passageways 52extending longitudinally through the body. To limit the movement of theball valve to secure approximately the same ei'-.

fective advance or pressure stroke of thepfitnns regardless of the speedof advance, the "dashpot cylinder 5| is formed with the annular stop 52a which is engageable with the upper end of the plunger. The cylinder isadjustably mounted on' v the low pressure piston as by being threadedinto the annular flange 50. To locktthe collar 59 and the dashpotcylinder 5]. in their various adjusted positions, I. preferablylongitudinally slot thean- I nular flange 50 in' registration with theradial grooves 41, longitudinally slot the upper end por-.

tion of the dashpot cylinder 5| and form penings in the collar 58 toreceive a lock wire 54. The

coil spring 51 is ofa strength suiflcient to hold the ball valve 5| toits seat 52 against the effort exerted by the braking fluid in the lowpressure cylinder 2 until a pressure of the braking 'fluid predeterminedby the adjustment of the collar 4 59 is created. However, the strengthof the coil pressure control device so that the coil spring; I

ball valve to become unyields,to permit the seated. l 4

It will be noted.- that the .011 position of the piston rod 5 isdetermined by the dashpot cylinder 5! which is adjustably carried by thelow pressure piston 5. The dashpot cylinder 51 abuts the dashpot plunger55, which isengaged by the ball valve 5|, which latter in turn isengaged by the plunger 53 by means of the retracting spring 39.

Assuming the parts to be in the oil position,

as shown in Figure Lthehigh pressure cylinder I is in communication withthe low pressure cyl' inder 2 and the low pressure cylinder 2 is incommunication with the reservoir 3. Upon downward pull of the piston rod6, its valve 35 will seat upon the valve seat 22 to close communicaheldupwardly by the piston rod Iowpressurecylinder 2 through'the piston rod.Atvthe-sametime, the. spring 51 seats the ball valve-51 upon its seat52to close communication between the --low pressure-cylinder. land thereservoir. 3;: Continued downward movement of the piston rod-'6' compelsthe high pressure piston 4 and the low pressure piston 5 to move.downwardly in unison during, which time the braking fluidunder pressureis-forced from the low pressure-cylinder [through the ports 25 and pastthe resilient 1disc;.24 andsealing cup 24 into the high pressurecylinderl and the braking fluid in the latter cylinder is discharged through thedischarge port .16; However, when-pressure of the braking-fluidwithinthe low pressure cylinder 2 reaches a. predetermined point, thebraking fluid. 'in=the1lcwpressure cylinder unseats the ballvalve 5|,thereby placing the low pressure cylinder in :communication with thereservoir 3.

'Then. when the pressure .of the braking fluid withinthe high pressurecylinder I reaches a higher predetermined point the braking fluidwithinthe axial passageway 36 in the piston rod acts-upon the plunger 53to hold the same against the ball 5| inopen position, thereby completelyrelieving the braking fluid in the low pressure cylinder'from pressureexcept that of the hydraulic head of the braking fluid in the reservoir.Theunseating of the ball valve 5| takes place against the effort exertedby the coil spring 51and .the resistance offered by the dashpotcylinder'li I and dashpot plunger 56. The sealing ring 54 opposesfrictional resistance to the unseating movement of the plunger 53 tohold the plunger from movement until the pressure of the braking fluidin the high pressure cylinder is higher than the pressure of the brakingfluid in the low pressure cylinder when the ball valve is moved to openposition. The unseating movementof the ball valve is limited by the stop63 of the'cylinder engaging the plunger. At this time I the parts areinthe position indicated in Figure 2 and the fluid pressure within thelow pressure cylinder 2 is relieved by reason of the low pressurecylinder being placed in communication with the reservoir. As a result,continued downward movement of the piston rod causes the high pressurepiston only to discharge braking fluid through the discharge port. Whenthe piston rod is released, the coil springs 39 and 44 act to return thepiston rod and the pistons, respectively, to their off position.

With the construction as shown, the plunger.

53 is movedagainst the ball valve 5| when the pressure of the brakingfluid in the high presthe high pressure piston and the low pressurepiston, preferably by having a press fit with the 'reduced portion H ofthe sleeve 12 of the high pressurepiston and also by having the integralenlargement 13 abutting an annular shoulder formed at the upperend ofthe reduced portion H and held in-engagement therewith by the sealingcup" and the annular spacer 15. The uption'between' the high pressurecylinder l and the per end of the spacer is abutted by the annular bodyI of the low pressur piston. The constructio of the device for relievingthe fluid pressure in the low pressure cylinder 69 is the same as thatof Figures 1 to 4, inclusive, with the exception that the plunger 11 forunseating the ball valve is of a length such that the ball valve isseated when the parts are in off position. There is but one retractingcoil spring 18 which operates upon the piston rod to return the pistonrod and the pistons to their off position.

In the off position of the parts, as illustrated in Figure 5, the highpressure cylinder 66 is in communication through the passageways 65 withthe low pressure cylinder 69 and. the low pressure cylinder 69 is incommunication through the passageways 68v with the reservoir 19. The

. ball valve is seated to close the communication between the lowpressure cylinder and the reservoir through the low pressure piston.

the ball valve is unseated by the braking fluid in the low pressurecylinder and then when a higher predetermined pressure of the brakingfluid in the high pressure cylinder is reached, the braking fluid in thehigh pressure cylinder acts upon the plunger 11 to move the sameupwardly to hold the ball valve in open position, at which time the lowpressure cylinder is completely relieved from fluid pressure except thatof the hydraulic head of the braking fluid in the reservoir. movement ofthe piston rod the high pressure piston 64 acts only to discharge thebraking fluid. as illustrated in Figure 6.

Figure '7 illustrates another modification which differs essentiallyfrom the modifications of Figures 1 to 4, inclusive, and Figures 5 and 6in forming the upper end of the piston rod with the annular flange 8|for directly slidably engaging the plunger 82 for unseating the ballvalve. In this case, a suitable sealing ring 83 is provided in anannular groove in the plunger 82 for engaging the annular flange 8| toprevent the escape of the braking fluid through the axial pas-' sagewayin the piston rod and between the plunger-and the annular flange. Thissealing ring also functions in the same manner as the sealing ring 54 tooppose frictional resistance to the unseating movement of the plunger.

What I claim as my invention is:

1. A fluid pressure control device comprising a cylinder having adischarge port, a second cylinder of larger diameter than said firstmentioned cylinder, a fluid reservoir, a piston slidable in said firstmentioned cylinder, a second piston slidable in said second cylinder andmovable with said first mentioned piston, said second piston having apassageway therethrough for placing said second cylinder and reservoirin communication. a valve movable relative to said second piston forclosing said passageway, a piston rod for directly advancing saidpistons from off position, said piston rod being movable axiallyrelative to said first mentioned piston and having a passageway Upondownward pull on the pistonrod 10, the pistons As a result, duringcontinued downward a means between a resistance to a high pressure2,866,119 I for placing said cylinders incommunication and said lowpressure chamber, said mech a valve engageable with said flrstmentlonedpiscomprising a valve movableby the fluid in said ton to close said lastmentioned passageway and one or said chambers, a dashpot plungerengageto directly move said pistons from off position,

and a plunger engageable with said flrst mentioned valve in theoff-position of said piston rod to hold said first mentioned valve inopen position, said plunger also being movable relative to said pistonrod during the advance of the latter to permit said flrst mentionedvalve to move to closed position and then to hold said flrst mentionedvalve in open position under the fluid pressure created in said flrstmentioned cylinder.

2. A fluid pressure control device comprising a high pressure cylinder,9. low pressure cylinder, a reservoir, high pressure and low pressurepistons in said high pressure and low pressure cylinders, respectively,vancing said pistons a piston rod for directly adfrom oil position, saidpiston rod having a passageway in communication with said high pressurecylinder, said low pressure piston having a passageway therethroughforplacingsaid low pressure cylinderin communication with saidreservoir, a valve for controlling said last mentioned passageway, aplunger engageable with said valve and extending within said piston rodand subject to the pressure of the fluid within said piston rod,passageway, and the side of said plunger and the encircling portion ofsaid piston rod imposing the movement of said plunger.

3. A fluid pressure control device comprising cylinder, a low pressurecylinder, a reservoir, high pressure and low pressure pistons in saidhigh pressure and low pressure cylinders, respectively, a piston rod fordirectly ad vancing said pistons'from off position, said pistn rodhaving a passageway in communication with said high pressure cylinder,said low pressure piston having a. passageway therethrough for placingsaid low pressure cylinder in communication with said reservoir, a valvefor controlling said last mentioned gageable with said said piston rodand subject to the pressure of the fluid within said piston rodpassageway, and a sealing ring between the side of said plunger and theencircling portion of said. piston rod frictionally engaging saidplungen 4. A fluid a high passageway, a plunger ensaid valve.

5. A fluid pressure control device comprising a high pressure chamberhaving a discharge port, a low pressure chamber for discharging fluidinto said high pressure chamber, a reservoir, and a mechanism forplacing said low pressure chamber in communication with said reservoirwhen a predetermined pressure is created within one ,of said chambers torelieve the fluid pressure in valve and extending within pressurecontrol device comprising pressure chamber having a discharge port, alow pressure chamber for discharging fluid into plunger engageable ablewith said valve, an adjustable dashpot cyling movement of said plunger.

, movement of said valve, said controlling means 6.'A fluid pressurecontrol device comprising a high pressure cylinder, a low pressurecylinder, a reservoir, high pressure and tons in said high pressure andlow pressure cyl-V inders, respectively, said low pressure piston havinga passageway therethrough, a valve for controlling said passageway,means operable by the fluid in said high pressure cylinder for holdingsaid valve in open position, a dashpot plunger controlling movement ofsaid valve, a dashpot cylinder mounted on said low pressure piston andwithin which said plunger is slidable, and spring means mounted on saidlow pressure piston for resiliently resisting movement of said plunger.

7. A fluid pressure control device comprising pressure cylinder,areservoir having an opening,;a closure member for the openingdetachably secured to said reservoir, high pressure and low pressurepistons in said high pressure and low pressure cylinders respectiveiy,and mechanism for placing said low pressurefcylinder in communicationwith said reservoir when a predetermined pressure is created in one ofsaid cylindersto relieve the fluid pressure in said low pressurecylinder, said mechanism comprisingv a valve movable by the fluid insaid one of said cylinders, a dash pot plunger engageable with saidvalve, a dash pot cylinder within whichsaid plunger is slidable, saidcylinder being adjustably mounted on said low pre'ssurepiston, andspring means resisting movement of said plunger, said spring means alsobeing adjustably mounted on said'low pressure piston, said dash Dot,plunger, dash pot cylinder and spring means being located within saidreser voir for ready accessibility through the opening when said closuremember is detached. I

8. A fluid pressure control device. comprising a high pressure cylinder,a low pressure cylinder, a reservoir, high pressure tons in said highpressure and low pressure cylinders respectively, said low pressurepiston having a passageway therethrough for placing said low pressurecylinder in communication with said reservoir, a valvefor controllingsaid passageway, said valve being movable to open position by the fluidin one of said cylinders, and

means independent of the flow of fluid through said passageway forcontrolling the opening comprising a dash pot plunger engaging saidvalve and a dash pot cylinder slidably receiving,

said dash pot plunger.

9. A fluid pressure control device comprisingi low pressure producingmean and high pressure in said low producing means, a valve forrelieving pressure of fluid in said low pressure producing means uponthe attainment of a predetermined pressure pressure producing means,adjustable spring mean resisting movement of said valve,

and stop means adjustable independently of said spring means forlimiting movement of said valve.

/' LUDWIG A. MAJNERI.

low pressure piss I and low pressure pis-

